Sensitivity measuring system and method for self-contained hydrophone
Through the self-contained hydrophone sensitivity measurement system and Fourier spectrum analysis method, the problem of difficult measurement of the sensitivity of the self-contained hydrophone is solved, and a rapid and accurate sensitivity evaluation is achieved, which improves the measurement efficiency and accuracy of the self-contained hydrophone.
Patent Information
- Application Number
- CN202510364433.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-07-25
AI Technical Summary
The prior art lacks effective methods to accurately and quickly measure the sensitivity of self-contained hydrophones, making it difficult to evaluate its acoustic signal detection capability underwater.
A self-contained hydrophone sensitivity measurement system is designed, including a signal processing module, a signal generator, a power amplifier, a filter, an auxiliary transmitter and a standard hydrophone. Combined with the Fourier spectrum analysis method, the sensitivity of the self-contained hydrophone is obtained through the self-contained hydrophone recording voltage.
It realizes automatic measurement of the sensitivity of self-contained hydrophones, improves measurement efficiency and accuracy, can quickly batch processing and record voltages, and improves the sensitivity evaluation ability of hydrophones.
Smart Images
Figure CN120369099A_ABST
Abstract
Description
Technical Field:
[0001] The present invention belongs to the technical field of underwater acoustic measurement, and particularly relates to a self - contained hydrophone sensitivity measurement system and method. Background Art:
[0002] Underwater acoustic detection technology has important applications in fields such as marine defense, marine resource exploration, and seismic wave detection. Hydrophones can convert underwater acoustic signals into electrical signals and are important devices for underwater acoustic detection. When traditional hydrophones are used for deep - sea measurement, they need to be equipped with long cables and it is difficult to achieve long - term measurement and monitoring of underwater acoustic signals.
[0003] Compared with traditional hydrophones, self - contained hydrophones have internal integrated circuits, network ports, and chips, which can process signals in real time and realize networking of underwater acoustic detection devices. Moreover, since self - contained hydrophones have a data storage function, when working in water, the collected data can be stored at any time, making them suitable for long - term deployment in the marine environment. Therefore, self - contained hydrophones have great advantages in the field of marine detection of weapons and equipment and can play an important role in future deep - sea communication and distributed detection networks.
[0004] The sensitivity of a self - contained hydrophone is an important item in its performance indicators, which directly affects the ability of the hydrophone to detect underwater acoustic signals. Before using a self - contained hydrophone, it is necessary to accurately measure its sensitivity, but there is currently no mature method for testing the sensitivity of self - contained hydrophones. For conventional hydrophones, since they do not have an internal storage device, when testing their sensitivity, the open - circuit voltage of the hydrophone can be measured by a digital oscilloscope, and combined with the underwater acoustic pressure at the location where the hydrophone is located, the sensitivity of the hydrophone can be measured. However, the acoustic signals collected by self - contained hydrophones cannot be directly measured by a digital oscilloscope, so it is difficult to accurately and quickly measure their sensitivity. Therefore, a new measurement method is urgently needed. Summary of the Invention:
[0005] The technical problem to be solved by the present invention is to provide a self - contained hydrophone sensitivity measurement system and method. The present invention uses the method for recording voltage acquisition of a self - contained hydrophone and combines it with the method for measuring the sensitivity of a self - contained hydrophone to measure the sensitivity of the self - contained hydrophone.
[0006] The technical solution of the present invention is to provide a self - contained hydrophone sensitivity measurement system, including
[0007] A self - contained hydrophone signal processing module, which is used to process the signals collected by the self - contained hydrophone and obtain the voltage at each frequency point;
[0008] A signal generator, which is used to output a single - frequency continuous signal with adjustable amplitude and frequency, as well as a single - frequency sine pulse signal;
[0009] A power amplifier is used to amplify the signal output by a signal generator and apply it to an auxiliary transmitter.
[0010] A filter is used to filter the signal received by a standard hydrophone and has an adjustable bandwidth band-pass filtering function.
[0011] An auxiliary transmitter is used to generate the sound field required for measuring a self-capacitance hydrophone in water.
[0012] A standard hydrophone is used to receive the signal transmitted by a transmitting transducer and measure the underwater sound pressure.
[0013] A PXI controller and an acquisition card are used to program and control electronic instrument devices and calculate the sensitivity of the self-capacitance hydrophone based on the acquired data.
[0014] Preferably, the self-capacitance hydrophone signal processing module processes the signal collected by the self-capacitance hydrophone and obtains its recorded voltage. The specific operations are as follows.
[0015] S1. Each time, read the signal collected by the self-capacitance hydrophone with a length of time T0, denoted as x(n), and the number of data points in the x(n) signal is denoted as N.
[0016] S2. According to Equation (1), perform spectral analysis on x(n) to obtain its spectrum P(k):
[0017]
[0018] In the formula, k is the ordinal number of the spectral line; P(k) is the amplitude of the spectral line, with the unit of decibel (dB).
[0019] S3. According to Equation (2), find the highest spectral line in the spectrum:
[0020]
[0021] S4. According to Equation (3), determine whether the power of the highest spectral line P(k max ) is higher than a specific magnitude than the background noise far from the measurement frequency band.
[0022]
[0023] In the formula, f1 and f2 are the lower and upper limit frequencies of the noise frequency range far from the measurement frequency band; P s (f) is the power spectral function of the signal x(n).
[0024] S5. According to Equation (4), determine whether the frequency where the highest spectral line P(k max ) is located is the 1 / 3 octave center frequency f0 within the measurement frequency range.
[0025]
[0026] S6. If the frequency where P(k max ) is located is the 1 / 3 octave center frequency point f0, then perform digital filtering on x(n) to obtain the filtered signal x fil (n); if the frequency where P(k max ) is located is not the 1 / 3 octave center frequency point f0, then return to step S1 to re-read the data;
[0027] S7. Use the extreme value method to find the steady-state signal x filter (n) in x sta (n);
[0028] S8. Calculate the effective value U(f0) of x sta (n).
[0029] Preferably, in step S7, the method for obtaining the steady-state signal xsta(n) is as follows: Denote the first derivative of xfilter(n) as x fil ‘ ter (n), and the second derivative as x" filter (n). According to Equation (5), obtain all the positive extreme values of xfilter(n),
[0030]
[0031] that is, the point n0 where the first derivative of x filter (n) is greater than 0 and the second derivative is equal to 0 is the positive extreme value point of the signal x filter (n). Calculate the center position of the separated pulse through the extreme value points, and take m waves before and after the center position to form an analysis signal of 2m sine waves as the steady-state sound signal x sta (n).
[0032] Preferably, in step S8, the method for calculating the effective value of x sta (n) is as follows: Calculate the effective value U(f0) of x sta (n) according to Equation (6).
[0033]
[0034] In the formula, N0 is the number of data points in the x sta (n) signal, and f s is the sampling rate of the self-capacitance hydrophone.
[0035] Preferably, in S4, according to Equation (3), determine whether the power of the highest spectral line P(k max ) is more than 20 dB higher than the background noise far from the measurement frequency band.
[0036] Preferably, the maximum allowable error of the output amplitude of the signal generator is not greater than ±2%.
[0037] Preferably, the linear distortion of the power amplifier is not greater than ±2%.
[0038] The present invention can utilize the above-mentioned self-capacitance hydrophone sensitivity measurement system to generate the sound field required for measuring the sensitivity of the self-capacitance hydrophone, place the self-capacitance hydrophone in the sound field, and collect and record the sound signals at all measurement frequency points. By using the method for obtaining the recorded voltage of the self-capacitance hydrophone and combining with the method for measuring the sensitivity of the self-capacitance hydrophone, the sensitivity of the self-capacitance hydrophone can be measured.
[0039] Therefore, the present invention also provides a measurement method based on the above-mentioned self-capacitance hydrophone sensitivity measurement system. By using the measurement system, the sound field required for measuring the sensitivity of the self-capacitance hydrophone is generated, the self-capacitance hydrophone is placed in the sound field, and the following operations are performed:
[0040] Step 1: Connect the self-capacitance hydrophone according to the requirements of the specification, and set the working parameters and check its working state through the self-capacitance hydrophone control software. When a vibration or sound pressure signal acts on the sensing unit of the self-capacitance hydrophone, the self-capacitance hydrophone should generate a corresponding electrical signal.
[0041] Step 2: Install the auxiliary transmitter, the standard hydrophone, and the self-capacitance digital hydrophone on the motion positioning mechanism, and make the reference sound centers of the three be on the same straight line. Measure and record the distance between the reference sound centers of the auxiliary transmitter and the standard hydrophone as d FH and the distance between the reference sound centers of the auxiliary transmitter and the self-capacitance hydrophone as d FX , and make the calibration directions of the standard hydrophone and the self-capacitance hydrophone face the auxiliary transmitter directly.
[0042] Step 3: Set the signal generator to generate a single-frequency sine pulse signal required for calibration, adjust the gain of the power amplifier to excite the auxiliary transducer to generate the sound field required for measurement, and observe the signal of the standard hydrophone. The signal-to-noise ratio should meet the requirement of not less than 20 dB.
[0043] Step 4: Measure the excitation currents I FH and I FX of the auxiliary transducers in the auxiliary transmitter and the standard hydrophone, and between the auxiliary transmitter and the self-capacitance hydrophone respectively, as well as the open-circuit voltage U FH of the standard hydrophone and the voltage U FX recorded by the self-capacitance hydrophone. Then, the sensitivity level of the measured self-capacitance hydrophone can be expressed as:
[0044] M = 20lgU FX - 20lgI FX - 20lgU FH + 20lgIFH +20lgd FX -20lgd FH +M H (7)
[0045] In Equation (7), M H is the sensitivity level of the standard hydrophone.
[0046] Compared with the prior art, the present invention has the following advantages:
[0047] The present invention adopts a method for obtaining the recorded voltage of a self - contained hydrophone based on Fourier spectrum analysis, which can realize the batch automatic processing of the recorded voltage of the self - contained hydrophone, so as to obtain the effective value of the measurement signal received by the digital hydrophone; through the present invention, the automatic measurement of the sensitivity of the self - contained hydrophone can be realized, the processing rate of the recorded voltage of the self - contained hydrophone can be improved, and thus the efficiency and accuracy of the sensitivity measurement of the self - contained hydrophone can be improved. Description of the Drawings:
[0048] Figure 1 is a schematic diagram of a system for measuring the sensitivity of a self - contained hydrophone of the present invention.
[0049] Figure 2 is a flow chart for obtaining the recorded voltage of the self - contained hydrophone of the present invention.
[0050] Figure 3 is a schematic diagram of reading the signal collected by the self - contained hydrophone with a time length of T0. Detailed Embodiment:
[0051] The following further describes the present invention in detail in conjunction with the drawings:
[0052] A system for measuring the sensitivity of a self - contained hydrophone, as Figure 1 shown, includes a self - contained hydrophone signal processing module 1 for processing the signals collected by the self - contained hydrophone and obtaining the voltage at each frequency point; a signal generator 4 for outputting a single - frequency continuous signal and a single - frequency sine pulse signal with adjustable amplitude and frequency, and the maximum allowable error of the output amplitude is not greater than ±2%; a power amplifier 5 for power - amplifying the signals output by the signal generator and applying them to the auxiliary transmitter, with a linear distortion not greater than ±2%; a filter 2 for filtering the signals received by the standard hydrophone, having an adjustable band - width band - pass filtering function; an auxiliary transmitter 6 for generating the sound field required for measuring the self - contained hydrophone in water; a standard hydrophone 7 for receiving the signals transmitted by the transmitting transducer and measuring the underwater sound pressure; a self - contained hydrophone 8, the self - contained hydrophone to be measured; a PXI controller and an acquisition card 3 for programming and controlling electronic instrument devices and calculating the sensitivity of the self - contained hydrophone according to the collected data.
[0053] Among them, the self - contained hydrophone signal processing module processes the signals collected by the self - contained hydrophone and obtains its recorded voltage. That is to say, it includes a method for obtaining the recorded voltage of the self - contained hydrophone, such as Figure 2 shown, mainly including the following steps
[0054] S1. Each time, read the original data collected by the self - contained hydrophone with a length of time T0. As Figure 3 shown, here T0 = 0.1s is taken, denoted as x(n), and the number of data points in the x(n) signal is denoted as N;
[0055] S2. According to Equation (1), perform spectral analysis on x(n) to obtain its spectrum P(k):
[0056]
[0057] In the formula, k is the ordinal number of the spectral line; P(k) is the amplitude of the spectral line, with the unit of decibel (dB);
[0058] S3. According to Equation (2), find the highest spectral line in the spectrum:
[0059]
[0060] S4. According to Equation (3), judge whether the power of the highest spectral line P(k max ) is more than 20 dB higher than the background noise far from the measurement frequency band;
[0061]
[0062] In the formula, f1 and f2 are the lower and upper limit frequencies of the noise frequency range far from the measurement frequency band; when the test frequency is higher than 1 kHz, f1 = 630 Hz and f2 = 800 Hz are taken; P s (f) is the power spectral function of the signal x(n).
[0063] S5. According to Equation (4), judge whether the frequency where the highest spectral line P(k max ) is located is the 1 / 3 - octave center frequency point f0 within the measurement frequency range;
[0064]
[0065] S6. If the frequency where P(k max ) is located is the 1 / 3 - octave center frequency point f0, then perform digital filtering on x(n) to obtain the filtered signal x fil (n); if the frequency where P(k max ) is located is not the 1 / 3 - octave center frequency point f0, then return to step S1 to read the data again;
[0066] S7. Use the extreme value method to find x filter The steady-state signal x in (n) sta (n);
[0067] S8. Calculate to obtain x sta The effective value U(f0) of (n).
[0068] As an implementation manner, in step S7, the method for obtaining the steady-state signal x sta (n) is as follows: x filter The first derivative of (n) is denoted as x fil ‘ ter (n), and the second derivative is denoted as x" filter (n). According to formula (5), obtain all the positive extreme values of xfilter(n),
[0069]
[0070] That is, the point n0 where the first derivative of x filter (n) is greater than 0 and the second derivative is equal to 0 is the positive extreme value point of the signal x filter (n). Calculate the center position of the separated pulse through the extreme value points, and take 2 waves before and after the center position to form an analysis signal of 4 sine waves as the steady-state acoustic signal x sta (n).
[0071] As an implementation manner, in step S8, the method for calculating the effective value of x sta (n) is as follows: Calculate the effective value U(f0) of x sta (n) according to formula (6).
[0072]
[0073] In the formula, N0 is the number of data points in the x sta (n) signal, and f s is the sampling rate of the self-capacitance hydrophone.
[0074] A measurement method for a self-capacitance hydrophone sensitivity measurement system based on the above. Using the measurement system, generate the sound field required for self-capacitance hydrophone sensitivity measurement, place the self-capacitance hydrophone in the sound field, and collect and record the sound signals at all measurement frequency points. Use the method for obtaining the recorded voltage of the self-capacitance hydrophone and combine it with the self-capacitance hydrophone sensitivity measurement method to measure the sensitivity of the self-capacitance hydrophone. The specific operations are as follows:
[0075] Step 1. Connect the self-capacitance hydrophone, set the working parameters and check its working state. When a vibration or sound pressure signal acts on the sensing unit of the self-capacitance hydrophone, the self-capacitance hydrophone should generate a corresponding electrical signal;
[0076] Step 2: Install the auxiliary transmitter, the standard hydrophone, and the self - contained digital hydrophone onto the motion positioning mechanism, and align the reference acoustic centers of the three in a straight line. Measure and record the distance between the reference acoustic centers of the auxiliary transmitter and the standard hydrophone as d FH , and the distance between the reference acoustic centers of the auxiliary transmitter and the self - contained hydrophone as d FX , and align the calibration directions of the standard hydrophone and the self - contained hydrophone directly towards the auxiliary transmitter;
[0077] Step 3: Set the signal generator to generate a single - frequency sine pulse signal required for calibration, adjust the gain of the power amplifier to excite the auxiliary transducer to generate the sound field required for measurement, and observe the signal of the standard hydrophone. The signal - to - noise ratio should meet the requirement of not less than 20 dB;
[0078] Step 4: Measure the excitation currents I FH , I FX of the auxiliary transducers in the auxiliary transmitter and the standard hydrophone, and the auxiliary transmitter and the self - contained hydrophone respectively, as well as the open - circuit voltage U FH of the standard hydrophone and the voltage U FX recorded by the self - contained hydrophone. Then, the sensitivity level of the measured self - contained hydrophone can be expressed as:
[0079] M = 20lgU FX - 20lgI FX - 20lgU FH + 20lgI FH + 20lgd FX - 20lgd FH + M H
[0080] In the formula, M H is the sensitivity level of the standard hydrophone.
[0081] Combining the characteristics that the self - contained hydrophone can automatically collect and store signals, the present invention designs a method for obtaining the recorded voltage of the self - contained hydrophone, which can realize the batch automatic processing of the recorded voltage of the self - contained hydrophone, thereby obtaining the effective values of the measurement signals at different frequency points received by the digital hydrophone, improving the processing rate of the recorded voltage of the self - contained hydrophone, and thus enhancing the efficiency and accuracy of the sensitivity measurement of the self - contained hydrophone.
[0082] The above is only an illustration of the preferred embodiments of the present invention, and it should not be construed as a limitation to the claims. All equivalent process transformations made using the description of the present invention are included within the scope of the patent protection of the present invention.
Claims
1. A self - contained hydrophone sensitivity measurement system, characterized in that: including a self - contained hydrophone signal processing module, which is used to process the signals collected by the self - contained hydrophone and obtain the voltage at each frequency point; a signal generator, which is used to output a single - frequency continuous signal with adjustable amplitude and frequency, and a single - frequency sine pulse signal; a power amplifier, which is used to amplify the power of the signals output by the signal generator and apply them to the auxiliary transmitter; a filter, which is used to filter the signals received by the standard hydrophone and has an adjustable band - width band - pass filtering function; an auxiliary transmitter, which is used to generate the sound field required for measuring the self - contained hydrophone in water; a standard hydrophone, which is used to receive the signals transmitted by the transmitting transducer and measure the underwater sound pressure; a PXI controller and an acquisition card, which are used to program - control the electronic instrument devices and calculate the sensitivity of the self - contained hydrophone according to the collected data.
2. The self - contained hydrophone sensitivity measurement system according to claim 1, characterized in that: The self - contained hydrophone signal processing module processes the signals collected by the self - contained hydrophone and obtains its recorded voltage. The specific operations are as follows. S1. Read the signals collected by the self - contained hydrophone with a length of time T0 each time, denoted as x(n). The number of data points in the x(n) signal is denoted as N; S2. According to Equation (1), perform spectral analysis on x(n) to obtain its spectrum P(k): where k is the ordinal number of the spectral line; P(k) is the amplitude of the spectral line, and the unit is decibel; S3. According to Equation (2), find the highest spectral line in the spectrum: S4. According to Equation (3), determine whether the power of the highest spectral line P(k max ) is higher than the background noise far from the measurement frequency band by a specific magnitude; where f1 and f2 are the lower and upper frequency limits of the noise frequency range far from the measurement frequency band; P s (f) is the power spectral function of the signal x(n). S5. According to Equation (4), determine whether the frequency where the highest spectral line P(k max ) is located is the 1 / 3 octave center frequency point f0 within the measurement frequency range; S6. If the frequency where P(k max ) is located is the 1 / 3 octave center frequency point f0, then perform digital filtering on x(n) to obtain the filtered signal x fil (n); if the frequency where P(k max ) is located is not the 1 / 3 octave center frequency point f0, then return to step S1 to reread the data; S7. Use the extreme value method to find x filter The steady-state signal x in sta (n); S8. Calculate to obtain x sta The effective value U(f0) of (n).
3. The self - contained hydrophone sensitivity measurement system according to claim 2, wherein: In step S7, the method for obtaining the steady-state signal xsta(n) is as follows: Denote the first derivative of xfilter(n) as x fil ‘ ter (n), and the second derivative as x" filter (n). According to Equation (5), obtain all the positive extreme values of x filter (n), That is, x filter (n) where the first derivative is greater than 0 and the second derivative is equal to 0 at the point n0 is the positive extreme point of the signal x filter (n). Calculate the center position of the separated pulse through the extreme point, and take m waves before and after the center position to form an analytical signal of 2m sine waves as the steady-state sound signal x sta (n).
4. The self - contained hydrophone sensitivity measurement system according to claim 2, characterized in that: In step S8, x sta The method for calculating the effective value of (n) is as follows: Calculate x according to Equation (6) sta The effective value U(f0) of (n). where N0 is x sta (n) the number of data points in the signal, f s is the sampling rate of the self - contained hydrophone.
5. The self - contained hydrophone sensitivity measurement system according to claim 2, wherein: In S4, according to Equation (3), it is determined whether the power of the highest spectral line P(k max ) is more than 20 dB higher than the background noise far from the measurement frequency band.
6. The self-capacitance hydrophone sensitivity measurement system according to claim 1, characterized in that: The maximum allowable error of the output amplitude of the signal generator is not greater than ±2%.
7. The self - contained hydrophone sensitivity measurement system according to claim 1, characterized in that: The linear distortion of the power amplifier is not greater than ±2%.
8. A measurement method for a self - contained hydrophone sensitivity measurement system according to any one of claims 1 - 7, characterized in that: Using the measurement system, generate the sound field required for measuring the sensitivity of the self - contained hydrophone, place the self - contained hydrophone in the sound field, and perform the following operations: Step 1. Connect the self - contained hydrophone, set the working parameters and check its working state. When a vibration or sound pressure signal acts on the sensing unit of the self - contained hydrophone, the self - contained hydrophone should generate corresponding electrical signals; Step 2: Install the auxiliary transmitter, the standard hydrophone, and the self-contained digital hydrophone onto the motion positioning mechanism, and align the reference acoustic centers of the three in a straight line. Measure and record the distance between the reference acoustic centers of the auxiliary transmitter and the standard hydrophone as d FH , and the distance between the reference acoustic centers of the auxiliary transmitter and the self-contained hydrophone as d FX , and ensure that the calibration directions of the standard hydrophone and the self-contained hydrophone face the auxiliary transmitter directly; Step 3. Set the signal generator to generate a single - frequency sine pulse signal required for calibration, adjust the gain of the power amplifier to excite the auxiliary transducer to generate the sound field required for measurement, and observe the signals of the standard hydrophone. The signal - to - noise ratio should meet the requirement of not less than 20 dB; Step 4: Measure the excitation currents I FH and I FX of the auxiliary transducer in the auxiliary transmitter and the standard hydrophone, and the auxiliary transmitter and the self - contained hydrophone, as well as the open - circuit voltage U FH of the standard hydrophone and the voltage U FX recorded by the self - contained hydrophone. Then, the sensitivity level of the measured self - contained hydrophone can be expressed as: M = 20 lg U FX - 20 lg I FX - 20 lg U FH + 20 lg I FH + 20 lg d FX - 20 lg d FH + M H where M H is the sensitivity level of the standard hydrophone.